Photographic light-sensitive diazo element



Patented May 1, 1951 Andrew Bradshaw Jennings, New Brunswick, and OtisWillard Murray, Fords, N. J assignors to E. I. du Pont de Nemours &Company, Wilmington, Del., a corporation of Delaware No waiting.Application August 29, 1946, Serial No. 693,802

8 Claims.

This invention relates to photography and, more particularly, tolight-sensitive photographic elements containing light-sensitivediazonium salts and to compositions and preparing the same. Still moreparticularly it relates to photographic elements comprisinga supportbearing a hydrophilic color former layer having intimately dispersedtherethrough light-sensitive diazonium salts and to processes for makingsuch layers.

An object of this invention is to provide a new type of light-sensitivephotographic element. A more specific object is to provide such anelement which contains light-sensitive diazonium salts. A further objectis to provide such an element which may be processed rapidly to yieldreproductions of high contrast with good resolving power and definition.A still further object is to provide a simple and economical method forpreparing such elements. Still other objects will be apparent from thefollowing description of the invention.

The novel photographic elements of this invention consist of a supportwhich bears at least one water-permeable layer composed of ahydrophilic, polymeric color former which has intimately dispersedtherethough light-sensitive diazonium salts. The hydrophilic, polymericcolor formers consist of synthetic, organic, polymeric com pounds whichcontain a polymeric chain nucleus and include in their molecularstructure nuclei which are capable of forming azomethine or indophenoldyes on color coupling development of exposed silver halides. Thesecolor formers are also capable ofcoupling with diazo compounds to formdiazo dyes. Hence when light-sensitive diazonium salts are incorporatedwith them, the latter compounds couple under the conditions suitable fordevelopment of light-sensitive :diazonium salts to form polymeric azodyes.

The novel elements consist essentially of two components, namely, thehydrophilic, polymeric color former and the light-sensitive diazoniumsalt. Hence they are quite simple to fabricate and process. The coatingtechniques for preparing the emulsions or light-sensitive coatings aresimplified by reason of the two-component nature of the final product.

The coating solutions may be prepared by dissolving the. hydrophilic,polymeric color former suitable solvent or mixture of solvents, such asmethanol, ethanol, diouane, etc, and mixtures of such solvents withwater. The hydrophilic, polymeric color former and the light-sensitivedazonium compound may be dissolved in the same solution by adding themseparately or simultaneously or they may be separately dissolved indifferent portions of the same solvent and admixed with stirring.Stabilizing agents for the diazonium salts can be incorporated with thecoating solutions if desired. The resulting solutions may then beapplied to a support to form a thin layer and dried. The preparation ofthe solutions and the coating operations should, of course, be carriedout in the absence of actinic radiations which would aiiect thelight-sensitive diazonium compounds;

An alternative method of preparing the lightsensitive coatings or layersis to dissolve the hydrophilic, polymeric color former in a solution andto coat this upon a support to form a layer which is then dried. Thedried layer is then impregnated with a solution containing thelightsensitive diazonium compound. The latter solution freely permeatesthroughout the entire layer and as it dries it deposits thelight-sensitive salt uniformly throughout the layer.

In the preferred form of the invention there are used hydrophilichydroxyl color formers which consist of a linear polymer chain which hasattached, to recurring carbon atoms thereof, a hydroxyl group and, toother recurring carbon atoms, color former nuclei capable of formingazomethine or indophenol dyes through a covalent bond. The color formernuclei may be attached to recurring carbon atoms of the polymer chainthrough ether or acetal linkages. The

and. light-sensitive diazonium compound in a preferred hydrophilic,hydroxyl polymer color formers, moreover, should have a polymer chaincontaining more than 200 carbon atoms.

Suitable synthetic hydroxyl polymers that may be connected to colorforming nuclei to produce the hydrophilic color forming hydroxylpolymers of the present invention include hydrolyzed polyvinyl esters,i. e., polyvinyl alcohols, hydrolyzed interpolymers of vinyl esters, e.g., vinyl acetate, vinyl propionate, and vinyl butyrate, etc., witholefins, e. g., ethylene, propylene, butene-l, and other vinylcompounds, e. g., acrylic acid, acrylic acid allcyl esters, alkylmethacrylates, vinyl chloride, vinyl cyanide, and maleic anhydride, andalso the partial esters, ethers, and acetals of such polymers. Thesepolymers may be connected to the color former nuclei by various chemicalgroupings or linkages, such as, for example, carbonamide, sulionamide,amino groups, acetal, ester, ether linkages, etc.

The color former nuclei or components of the above synthetic polymershave as active coupling groups a structure which may be represented as iI -o=o, C=N-, CEN

and others. The -CH2- group is usually pres ent between two such groups,for example,

I o o Gino o o CHZCN, -o o oH2o=N in a cylic or acyclic system. In allof the color former nuclei the hydrogen atoms in the coupling positionmay be replaced by groups which are readily eliminated in the couplingreaction, e. g., halogen, e. g., chlorine and bromine, sulionic acid,carboxylic acid, etc.

Suitable specific color formers of the above type are described inUnited States Patents 2,310,943, 2,320,422, 2,397,864, and 2,397,865.

The coating solutions described above may be applied to the support byany of the conventional coating procedures, e. g., by dipping, spraying,coating from hoppers by means of beading rollers, etc. They may beapplied to practically any type of support, such as metal, plastic,glass, transparent film base, water-prooied paper, cellulosederivatives, superpolymers, e. g., nylon, etc.

The invention will be further illustrated by the following examples.

Example I A 5% solution ofmeta(lhydroxynaphthalene-2-sulfoamido)benzaldehyde polyvinyl acetal(prepared as described in application Serial Number 667,111, filed May3, 1946, now U. S. Patent No. 2,433,572) was prepared in a waterethanolsolution containing 75 parts of the former and parts of the latter byweight. resulting solution was deposited on a baryta coated papersupport at a coating weight of 60 milligrams per square decimeter ofsaid acetal.

This structure is found in The resulting layer was dried at atemperature of about l050 C. in a current of air. solution of the zincdouble salt of diazotized p-amino-diethylaniline in water was suppliedto the layer. The entire operation was carried out in the absence ofactinic light. The resulting element, after drying, was exposed to apositive transparent image by means of a 500 watt 3200 K. lamp at adistance of three feet for ten minutes. The exposed element wassubsequently developed by fuming it with ammonia vapor for a period often minutes. A strong, positive image, which was brown in color, wasformed.

Example II A 5% solution of meta(p-[5-ethylcarbonato-3- methyl lpyrazoyl)benzamidolbenzaldehyde acetal of polyvinyl alcohol (prepared asdescribed in application Serial Number 667,126, filed May 8,1946, now U.S. Patent No. 2,476,988) was substituted for the acetal of Example I.The resulting element was exposed and developed as described in thatexample whereby a magenta image was formed.

Example III A 5% solution of meta(benzoylacetamido)benzaldehydepolyvinyl acetal (prepared as described in application Serial Number667,126, filed May 3, 1946, now U. S. Patent No. 2,464,597) was substituted for the acetal of Example I. The resulting element was exposedand processed as described in that example and a strong, orange imagewas obtained.

In place of the specific color formers of the above examples, there maybe substituted other hydrophilic polymeric color formers and especiallythose of the aforementioned patents with similar results.

Any organic solvent or mixture of solvents may be employed in preparingthe solutions as long as they are not reactive with the daizo compounds.Thus ketones, such as acetone, methyl ethyl ketone, cyclohexanone, etc.,cannot be used, while alcohols, e. g., methanol, ethanol, n-propanol,isopropanol, n-butanol, secondary butanol, etc; glycols, c. g., ethyleneglycol, diethylene glycol, propylene glycol; ethlyene glycol monomethyland monoethyl ethers; ethylene glycol dimethyl ether; tetrahydroiuran;esters, e. g., methyl acetate, ethyl acetate, ethyl propionate, ethylbutyrate, ethyl glycolate, ethyl methoxyacetate; hydrocarbons, e. g.,hexane, benzene; chlorinated hydrocarbons, e. g., chloroform, carbontetrachloride, ethylene dichloride, etc., can be used providing thatthey are solvents for all the constituents of the coating composition.

The preferred solvents or solvent solutions are those which arewater-miscible to the extent that 10% or more water can be dissolvedtherein. A small amount of water in the coating composition is desirableand aids in dissolving the diazonium compound and in securing an evenlightsensitive coating. Further, it is usually desirable to use thosewith an appreciable vapor pressure at normal temperatures so that dryingtimes will be as short as possible. However, in addition, portions (e.g., 5 to 25%) of solvent with a higher vapor pressure, e.g., boilingbetween and 260 C, are advantageous as an aid in securing even flow outsand smooth coatings.

In preparing solutions for application by spraying, it is oftendesirable to add an anti-foaming agent, e. g., long chain aliphaticalcohol, e. g.,

decylfdodecyl, tetradecyl, etc., so that an even coating free frombubbles may be obtained.

Y Y 1 1 I R ONH- NH2 /N -NH e I I Z X Z X and R NH:

naphthalene; l-aminodieth'ylaniline, 4-aminodiaminonapthalene,4-amino-diphenyl, 4-aminocarboethoxyaniline; methyl, 4amino-2,5-dimethoxyphenyl urea; phenyl, 4-amino-'2,5-dichlorophenylurea. f

Any of the various known sensitizers, such as urea, thiourea, allylthiourea, thiosulfate, etc., and/or compounds which form double saltswith diazonium compounds, such as tin," zinc, or cadmium salts, of weakacids, e. g., tartaric, citric, succinic, boric, etc., may be employedin these compositions. The latter compounds prevent coupling prior toexposure.

It is also desirable in some cases to add pigments to the compositions.For instance, if the light-sensitive composition is to be applied to asurface which is dark in color or unpainted and it is desired to havethe maximum contrast, a pigment is added which is complementary in colorto that of the final azo dye produced in the drawing. Thus, if the dyeformed is black, a white pigment may be added, such as titanium dioxideor barium sulfate pigment. If the final colors are to be red, a greenpigment may be used, or if they are to be blue, a yellow pigment may beused or any other such combination.

Suitable diazo stabilizers which prevent decomposition of thelight-sensitive diazonium compounds when coated on metal plates, e. g.,ferrous metal plates, are metal deactivators and corrosion inhibitorswhich are unreactive toward diazonium salts. Compounds useful for thispurpose include water-soluble metal nitrites, e. g., alkali metalnitrites, alkyl nitrites, e. g., amyl nitrite; alkyl phosphates, e. g.,monododecyl phosphate, didodecyl phosphate; and aromatic phosphates, e.g., tricresyl phosphate. These compounds may be used in small amounts,e. g., 0.01 to 0.2% based on the total weight of the hydrophilic,polymeric color former used.

Self-supporting foils may be made by coating the hydrophilic, polymericcolor former solu- 6 tions onto-a smooth surface, drying the resultingfilm element, and Stripping it from thecasting surface.

The light-sensitive, hydrophilic, polymeric color former coatingcompositions hereof have the advantage that they form watei' permeablelayers which are free from tackiness so that the surface will not stickto other materials, even when stored. in a humid place. The resultinglayers have a tough, smooth surface and are not softened by'watersufficiently to cause scratching or marring when handled Wet.

The coating compositions of this invention have a wide utility and aregenerally useful where it is desired to copy a design, drawing,

lettering, plan, etc., onto any water-resistant surface.- Thus, in themanufacture of templates for-use in preparing parts of machinery,airplanes, boats, automobiles, electrical equipment, etc.,- thematerials to be used, such as metal, composition boards, etc., arecoated with the light-sensitive compositions ofthis invention, dried,exposedthrough the master drawing, and developed. The finished print,which adheres firmly and is an exact duplicate of the original, is usedto cutout the template. Stencils or lettered transparencies may also beused to reproduce directions, identification numbers,, etc., on parts orfinished articles of manufacture. Elements may also be prepared bycoating the light-sensitive solutions on flexible bases, such as filmbase, water-proofed paper, plastic sheeting, and the like. Such elementsmay be used to prepare permanent records or may be fastened adhesivelyto"permanent.supports, e.; g., metal, boards, etc. i

As many widely different embodiments of this invention can be madewithout departing from the spirit, and scope thereof, it is to beunderstood that the invention is ;not to be limited excep as defined bythe claims.

What is claimed is':- t.

l. Photographic element comprising a support bearing at least one layercomposed of a hydrophilic polymeric color former having light-sensitivediazonium compounds uniformly dispersed therethrough, said color formercontaining a multiplicity of recurring active groups which have astructure represented by the formula where n is a number taken from thegroup consisting of 0 and l.

2. Photographic element comprising a support bearing at least one layercomposed of a hydrophilic polymeric color former having light-sentitivediazonium salts uniformly dispersed therethrough, said color formercontaining a multiplicity of recurring active groups which have astructure represented by the formula where n is a number taken from thegroup consisting of 0 and l. p

3. Photographic element comprising a support bearing at least one layercomposed of a hydrophilic hydroxyl polymer color former havinglight-sensitive diazonium salts uniformly dispersed th rethrough, saidcolor former containing a multiplicity of recurring CH2--CHOH-- groupsand a multiplicity of recurring active groups which have a structurerepresented by the formula where n is a number taken from the groupconsisting of 0 and 1.

4. Photographic element comprising a support bearing at least one layercomposed of a hydrophilic polyvinyl acetal color former which contains amultiplicity of recurring CHzCHOH- groups and a multiplicity ofrecurring active groups which have a structure represented by theformula .where n. is a. number taken from the group con- :former havinglight-sensitive diazonium compound uniformly dispersed therethrough,said polyvinyl acetal color former containing a multiplicity ofrecurring extralinear active groups which have a structure representedby the formula where n is a number taken from the group consisting of 0and. 1.

6. A photographic element comprising a waterproofed paper supportbearing a layer composed of m (1-hydroxynaphthalene-2-su1fonamido)rbenzaldehyde polyvinyl acetal having a zinc double salt of diazotizedp-aminodiethyl aniline uniformly dispersed therethrough.

7. A photographic element comprising a water-proofed paper supportbearing a layer composed of m-(p-[5-ethylcarbonato-3-methy1- 1pyrazoybbenzamido] benzaldehyde polyvinyl acetal having a zinc doublesalt of diazotized p-aminodiethyl aniline uniformly dispersedtherethrough.

8. A photographic element comprising a waterproofed paper supportbearing a layer composed of m-(benzoylacetamido) benzaldehyde polyvinylacetal having a zinc double salt of diazotized p-aminodiethyl anilineuiformly dispersed therethrough.

ANDREW BRADSHAW JENNINGS. OTIS WILLARD MURRAY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,444,469 Kogel Feb. 6, 19231,756,400 Schmidt Apr. 29, 1930 2,282,001 Russell May 5, 1942 2,297,732Woodward Oct. 6, 1942 2,310,943 Dorough Feb. 16, 1943 2,318,352 AlinkMay 4, 1943 2,320,422 Frohlich June 1, 1943 2,342,620 Woodward Feb. 22,1944 2,397,864 Jennings et a1 Apr. 2, 1946 2,397,865 Jennings Apr. 2,1946 2,397,866 McQueen Apr. 2, 1946 2,397,867 Jennings Apr. 2, 19462,405,523 Sease Aug. 6, 1946 2,415,381 Woodward Feb. 4, 1947 2,415,382Woodward Feb. 4, 1947 2,423,460 McQueen July 8, 1947 FOREIGN PATENTSNumber Country Date 700,252 Germany Dec. 16, 1940

1. PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT BEARING AT LEAST ONE LAYERCOMPOSED OF A HYDROPHILIC POLYMERIC COLOR FORMER HAVING LIGHT-SENSITIVEDIAZONIUM COMPOUNDS UNIFORMLY DISPERSED THERETHROUGH, SAID COLOR FORMERCONTAINING A MULTIPLICITY OF RECURRING ACTIVE GROUPS WHICH HAVE ASTRUCTURE REPRESENTED BY THE FORMULA